1. Field of the Invention
This invention relates to pressure regulating valves, and in particular to valves installed in an air flowing duct or the like to provide for delivery of a regulated downstream pressure from an upstream pressure supplied in a normally relatively higher range of pressures. The invention is addressed especially to the meeting of an operational requirement that the valve open the duct more fully to flow therethrough as upstream pressure drops, reaching fully open position at a predetermined low upstream pressure below which continued flow is of no value, and that the valve close the duct to flow therethrough should upstream pressure continue to fall and drop below such predetermined low value.
2. Description of the Prior Art
Pressure regulating valves are known which attempt to establish and maintain a range of reduced downstream pressures. In no instance of which applicant and those others substantively involved in preparation of this application are aware, does the valve apparatus function in sequential steps involving a reversal of valve movement from fully open to fully closed positions while the pressure responded to is changing in a single direction.